A New Mechanism Explaining High Frequency Chatter Vibration Involving Tool Tip X-Y Looping in Fine Boring

Abstract The study deals with boring tool, which was found to exhibit chatter in fine boring operation occurring at high frequencies, more than 10,000 Hz, and causing reduced tool life. The boring tool was operated in a stage of a transfer-type machining equipment and used for making small diameter hole, 15mm (0.59in), in a hardened alloy steel of motorcycle engine component. The objective of the research is to identify the mechanism responsible for the onset of the high frequency chatter. To study the mechanism, cutting tests have been performed in analogous machining operation, as well as structural dynamics examination of boring tool using experimental modal analysis by sinusoidal excitation. The experimental study has revealed that the traditional knowledge of regenerative chatter can not fully explain the chatter mechanism, but the effect of regeneration, the imaginary part effect of inner modulation, and the X-Y looping of the tool tip are three relevant characteristics in the onset of the chatter. Those findings are included in a new theoretical chatter model of which validity is evaluated principally by computational analysis of energy supplied and dissipated in the cutting process-boring tool structure system per vibration cycle.